Method of blanching food products



April 4, 1961 c. M. ASHLEY METHOD OF BLANCHING FOOD PRODUCTS OriginalFiled Nov. 14, 1951 2 Sheets-Sheet 1 INVENTOR.

CARLYLE MARTIN ASHLEY BY ATTORNEY.

April 4, 1961 c. M. ASHLEY 2,978,325

METHOD OF BLANCI-IING FOOD PRODUCTS Original Filed Nov. 14, 1951 2Sheets-Sheet 2 FIG. 2

COOLING SPRAYING ,1 STATION COOLING EMPTYING STATION STATION BLANCHINGFILLING VENTING STATION STATION INVENTOR. CARLYLE MARTIN ASHLEYATTORNEY.

United States 2,918,325" 7 METHOD OF BLANCHING FOOD PRODUCTS CarlyleMartin Ashley, Fayetteville, N.Y., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Delaware Original application Nov. 14,1951, Ser. No. 256,315,

npw Patent No. 2,870,020, dated Jan. 20, 1959. Divrded and thisapplication June 2, 1958,-Ser. No. 739,142

1 Claim. (Cl. 99-1) I uct during the cooling operation.

In food .freezing, either domestic or commercial, it is essential toblanch or scald the food product, particularly" vegetables, beforethefreezing operation to destroy or render inactive the enzymes to preventthe appearance and taste of the frozen product being deleteriouslyaffected. While blanching is conducted to destroy the principal enzymes,overblanching should be avoided.

Blanching has generally been conducted by means of boiling water orsteam. Water blanching is not satisfactory for it results in a decreasein the nutritive value of the food product since a large proportion ofthe juices and dissolved solids such as vitamins and minerals are washedaway. It may result in a-relative loss in weight in the final productwhich is extremely serious in commercial applications since the productis sold by weight. The water supply too may affect the texture,appearance, odor, flavor, nutritive value or storage life of the productsince it may containmaterials injurious to any or all of such factors;to avoid damage to the food product from the water supply, it iscustomary in larger freezing plants to provide expensive water treatmentequipment.

In the steam blanching processes as heretofore conducted, the solidsdissolved in the condensate are not returned to the product but arewasted. A further dis advantage rests in the fact that in the processesused heretofore the product is washed with water when it is in a soft,porous condition to cool the same with resulting loss of a considerableadditional percentage of solids.

The chief object of the present invention is to eliminate, the presentdisadvantages of steam blanching and water cooling, v V

An object of'th'e present invention is to provide a method of steamblanching in which nutrients are returned to the food product prior tofreezing. The term nutrients is used herein to designate dissolvedsolids such as minerals, vitamins, proteins, carbohydrates, etc.

A further object is to provide a method of steam blanching in whichnutrients are returned to the food product during'the cooling operation.

l A still further object is to provide a method of steam blanching andcooling in which condensate and juices given off by the'food productduring the steaming operation are evaporated under vacuum while incontact with the food product to cool the same, to restore the original"a atent O weight and to return the dissolved solids to the foodproduct.

A still further object is to provide a method of blanching in whichsteam is introduced and air and other noncondensible gases are removedin such manner that a minimum of oxygen is in contact with the heatedfood product to cause oxidation.

A still further object is to prevent the reintroduction of bacteria tothe heat-sterilized food product by contact with non-sterile water.

A still further object is to provide apparatus for steam blanching andsubsequent cooling of food products adapted for commercial use.

A still further object is to provide blanching apparatus in whichcondensate is removed from the food product at the end of the heatingoperation.

A still further object is to provide apparatus to blanch a food productand to cool the same While returning dissolved solidsand juices theretoto restore its original cooling food products in which the steps consistin placing a heated vapor in contact with the food product to heat thesame, collecting nutrients given off by the food product during theheating operation, cooling the heated food product and distributing thecollected nutrients over the food product to restore substantially theoriginal nutrients, including vitamins and minerals.

This invention further relates to a method of blanching and coo-lingfood products in which the steps consist in circulating a heated vaporover a food product to heat the same while condensing at least a portionof the vapor upon the product, discontinuing the supply of heated vapor,and then creating a vacuum about the food product to evaporate liquidpresent on the surface of the food product to cool the same.

This invention further'relates to apparatus for blanching and coolingfood products which comprises, in combination, means for supplying aheated vapor over the food product to heat the same thereby condensingat least a portion of the vapor, means for collecting at least a portionof the nutrients given off by the food product when it is contacted bythe vapor, and means for distributing at least a portion of thecollected nutrients over the food product to restore a substantialportion of the original nutrient content. 3 d

The attached drawings illustrate preferred embodiments of the invention,in which Figure 1 is a view partly in section and partly in elevation ofa portion of a continuous blanching and cooling device for commercialuse; and

Figure 2 is a diagrammatic view illustrating the various stations of thedevice shown in Figure 1.

The device shown in Figures 1 and 2 is adapted for commercial blanchingconducted as a continuous operation. The device comprises a rotatablecontrol member mounted on a base 96 and carrying a plurality of vessels97 to receive food products. Vessels 97 are mounted on rollers 98running on a track 99 supported by the framework 100 of the device. Anysuitable means (not shown) may be provided to rotate the vesselscontinuously or step-by-step about the central member.

Each vessel 97 is provided with a cover 101 which may be raised orlowered and locked in place on the vessel by suitable lifting andlocking mechanism 102 actuated by means of a cam member 103. Mechanism102 includes a cam follower 104 mounted on an arm 105 pivoted at 106 andattached to a rod 107. Rod 107 is connected at the opposite end to asecond arm 108 pivoted at 109. Hook or finger members 110 are pivoted at111 on cover 101 and are connected by links 112, 113 to a central post114. Thus, as cam member 103 moves ,3. follower 104 downward, arm 105pivots aboutpoint 106 moving rod 107 downward. Downward movement of rod107 pivots arm 108 about pivot point 109 tending to raise cover 101 andto release fingers 110 clamping the cover to flange 115 on vessel 97.

Suitable mechanism shown at 116 is provided to tilt vessels 97 to emptytheir contents into a chute 117 leading to a continuous screen conveyor118.

Central member 95 contains ports 119, 120, 121 connected to vessels 97by flexible connections 122, 123, 124 for steam, condensate and as apurge line. Within member 95 are ported plates (not shown) connected byducts (not shown) to the ports 119, 120, 121. Depending upon the stationat which any vessel 97 is positioned, steam is supplied and the vesselis purged or a vacuum is drawn in the vessel and condensate is sprayedover the food product within the vessel. It will be appreciated each ofthese operations is performed automatically by the rotation of thecentral member and vessels.

A condenser 125 is provided to reduce the pressure in the vessel topermit the cooling operation to be conducted, being conenctcd throughconnection 122 to the vessel in accordance with the rotation of thecentral member. The usual water ejector 126 is connected to thecondenser 125 to purge non-condensible gases therefrom.

Cooling of the food product is accomplished by employing the condenser125 to reduce pressure in the vessel thereby evaporating liquid presenton the surfaces of the food product therein. Rewetting the food productmay be accomplished by spray nozzles 127 in the top of vessel 97 whichdistribute condensate over the surfaces of the products, the nozzlesbeing connected to a supply of condensate by connection 123 as shown.

Food product is suplied to each vessel by means of a belt (not shown)which feeds the product to a tray (not shown) which may be tiltedperiodically by the motion of the rotating central member 95 to supplythe food product to vessels 97. At a second station about the apparatus,the blanching and venting operations are performed. The coolingoperation is conducted at a third station. At a fourth station thecooling operation is continued while condensate is sprayed over the foodproduct in the vessel. At a fifth station the food product is emptiedfrom the vessel on the second conveyor belt or screen 118, condensateflowing through the screen and being collected in a pan or sump 128,condensate collected in pan 128 being delivered by the difference inpressure between atmosphere and vacuum over the surfaces of the foodproduct in a succeeding vessel or, if desired, it may be sprayed overthe surface of the food product on belt 118.

Nozzles 127 are connected by line 123 to condensate supply (sump 128,for example) in order to rewet the food product in the vessels 97 duringthe cooling operation.

Considering the operation of the device, a food product is supplied to avessel 97 at a first station. When the vessel moves to a second stationsteam is admitted to vessel 97 through connection 122. Simultaneously,air and noncondensible gases are vented from the bottom of vessel 97through purge line 124. The steam heats the food product in the vessel,some portion of the steam vapor condensing thereon. Condensate fiows tothe bottom of the vessel. Any excess of condensate may be drawn oilthrough a drain valve (not shown) for reuse during succeeding coolingcycles. At a third station, supply of steam to vessel 97 is discontinuedand pressure is decreased in the vessel by means of condenser 125thereby evaporating condensate to cool the food product. Vapor from thefood product, together with any non-condensible gases remaining invessel 97, is drawn into condenser 125. Removal of the vapor from vessel97 lowers the pressure therein, thus evaporating condensate collected onthe surfaces of he food product to cool the same. A foam breaker may beemployed as previously described; if desired the nozzle sprays may beutilized to break any foam. Condensate, including juices and nutrientsfrom previous batches, if desired, is then sprayed over the food productin the vessel at a fourth station, the cooling operation continuing, torewet the food product thereby recovering juices and water lost duringthe cooling operation and restoring the original weight or a greaterweight as previously described. Sufi'lcient condensate may be sprayed atthe end of the operation to submerge-the food product in vessel 97, thusassuring a maximum gain in weight. It will be appreciated the weight ofthe food product may be decreased slightly if desired or may beincreased appreciably as desirable in commercial blanching.

Thereafter, at a fifth station, the vacuum in vessel 97 is broken. Thecover 101 is released and raised automatically by mechanism 102 and thevessel is tilted by mechanism 116 permitting the food product to droptherefrom onto continuous belt 118.

If desired, an inner perforated metal container for the food product maybe employed. If such container be employed, the container is raised andinverted, rather than the vessel itself, to remove the food product fromthe vessel. Likewise, a hinged bottom may be provided for the vessel topermit the food product to be dropped upon the belt.

The present invention provides a simple, ready, economical method ofblanching food products and cooling the same which may be practiced incommercial blanching operations. The method provided by my inventionassures that juices and dissolved solids are returned to the foodproduct before freezing and restores substantially the intial weight ofthe product, which is of particular value in commercial operations. Thedevice may be employed to practice the invention as a domestic procedureand may be employed to practice the invention as a continuous process oras a batch process in commercial operation.

It will be appreciated if the food product is heated through the samerange as it is cooled, substantially no change in weight of the foodproduct will occur. The food will absorb substantailly all of the juicessince heating followed by cooling increases the absorptive capacity.

While I have described a preferred embodiment of the invention, it willbe understood the invention is not limited thereto since it may beotherwise embodied within the scope of the following claim.

I claim:

In a method of continuously blanching food products, the steps whichconsist in placing steam in contact with the food product in a vessel toheat the same and condensing a portion of the steam thereon at a firststation, discontinuing the supply of steam, collecting the condensateand nutrients from the food product reducing the pressure about the foodproduct at a second station to evaporate liquid present on the surfaceof the food product to cool the same, continuing the cooling operationwhile spraying condensate and nutrients over the surfaces of the foodproduct at a third station to return a substantial part of thecondensate and nutrients to the food product and removing the foodproduct from the vessel at a fourth station while collecing condensateand nutrients remaining in the vessel for supply to a food product atthe third station.

References Cited in the file of this patent UNITED STATES PATENTS2,373,521 Wigelsworth Apr. 10, 1945 2,403,871 McBcan July 9, 19462,418,5l9 McBeth Apr. 8, 1947 2,515,879 Korn .luiy 18, 1950 2,522,513Hemmeter Sept. 19, 1950 2,581,484 Helgerud Jan. 8, 1952 2,692,200 OlsonOct. 19, 1954 2,870,020 Ashley Ian. 20, 1959

